How do they get their asses so big?
Lipofilling? Implants? Both?
Most of it is camera angles and photoshop---especially with the Fabrola chick. She has wide hips (child birthing hips) so that helps. And she has a nice booty, not sista (West African genetics) booty, but a nice one. Then there are the mags that hire Photoshop artists like Nick from Slickforce (who does Kim K's "candid" shots), and the photographers who choose certain angles...you'll notice the women's tops look small and the booties look bigger.
Also, they'll have the women do certain things to "make" their booty "appear" bigger, like that Asian chick (who has a flat booty) pull her panties around her anal cleft and push up, while the cameraman is looking up, thereby creating an illusion of having a bigger booty.
Or they go get work done.